The goal of this project, is to isolate this disease gene and ultimately identify mutations causing the disorder. Toward this end we have enrolled over 175 patients with Treacher Collins syndrome, performed clinical and diagnostic examinations, and established lymphoblastoid cultures on blood samples from these patients. These cultures have been used as a source for karyotype and DNA genotype analyses. We have localized the gene to a region less than 1 Mb on human chromosome 5.